AU2007245509B2 - Motorized system for closing a building - Google Patents

Abstract

The invention relates to a motorized system for closing a building, of the roller shutter type with the particular feature that it has a two-phase asynchronous motor which comprises two windings (2; 3) and is combined with a speed-varying device (5).

Description

I MOTORISED SYSTEM FOR CLOSING A BUILDING FIELD OF THE INVENTION The present invention relates generally to the field of devices, apparatus, assemblies 5 and systems for closing a building of the type roller shutter, and their motorisation. BACKGROUND OF THE INVENTION Many motorised systems for closing a building, which are in addition associated with remote-control devices facilitating the control of their opening and closing, arc already known. 10 In the particular field of the type roller shutter, the driving motor is typically of the tubular type, so as to be positioned inside the winding-up tube onto which the apron of, for example, a roller shutter is designed capable of winding up. 15 This is usually an asynchronous motor with a phase-shift capacitor including a main winding and a secondary winding allowing not only reversing the direction of rotation of the motor, but in addition, through the phase shift of the current generated by the capacitor, generating a driving torque at the level of the rotor of this motor. The secondary winding is typically different from the main winding in that it has a different 20 resistance and inductance and thus facilitates starting of the motor. Because of manufacturing constraints, some manufacturers design imperfect single phase motors with a secondary winding, which is identical to the main winding. This obliges them to use a larger capacitor, which heats up. Obviously, the encapsulation of 25 such a motor in a casing made out of synthetic insulating material and its installation inside a winding-up tube of a building closing system or the like of the type roller shutter do not facilitate heat extraction. Turning back to the operation of this type of motor, the stator currents create a rotary 30 magnetic field in the stator, while the rotor is comprised of short-circuited leads which pass there through currents induced by the stator magnetic field.

2 The starting torque of such an asynchronous motor with a capacitor depends on the capacity of the latter. Anyway, this type of motor operates optimally, under nominal current-supply conditions, only beyond a determined speed of rotation. 5 This being said, within the framework of their application to, for example, roller shutters, it should be noted that, though nearly no power is required for unwinding an apron of such a roller shutter and only a low starting torque is sufficient, However, when winding the apron up inertia of the unwound apron needs to be overcome. 10 When the apron of the roller shutter is fully unfolded and the openings between the hinged slats forming said apron are closed, the required torque during the first turns of rotation is reduced. However, when a roller-shutter apron is in a partially, even nearly fully unfolded situation, without the openings between the slats being closed, the required torque heavily loads the motor. For this purpose it is desirable that a motor is 15 capable of producing a high starting torque in to overcome the reverse torque that the weight of the apron. It is therefore typical, in this field of application of the type roller shutter, to use motors with a nominal power much higher than the power that is required for most of the range 20 of travel of the corresponding apron. Although this increases cost, it also increases the range of shutters that the motors can be used with by providing a plurality of motors with different powers to cover a full range of roller shutters one wants to motorise. In addition, the extra power of the motor, which is useful only during the starting 25 phase, i.e. during a transient phase in which the motor does not operate in an optimal way, results in heavily loading the mechanical elements of, for example a roller shutter, whether in the event of an unexpected blocking or in the event of a stoppage controlled by a manual or automated controller of the closing system. 30 It is in particular usual to ensure the stoppage of the motor, at the travel end for unwinding or winding-up the apron of the type roller shutter, for example through measuring the phase shift between current and voltage, This phase shift results from an 3 increase of the load applied to the motor, which results, in this case, from the arrival at the lower of upper travel end of the apron. Under such circumstances, one understands very well that, before the interruption of the current supply to the motor occurs, the latter exerts an excessive strain on the mechanical elements of, for example a roller 5 shutter, due to its over-dimensioning. It should also be noted that this type of motor is usually provided with an electromagnetic brake operating in the absence of current. Of course, the higher the power of the motor, the more this brake is loaded and must be oversized accordingly. 10 Besides this low starting torque produced by an asynchronous motor with main and secondary windings, this under nominal current-supply conditions, in this case a nominal voltage of 230 Volts and a frequency of 50 Hertz, there is also the problem of the network-voltage variation. In other words, this voltage of the current-supply 15 network of a dwelling is not constant and equal to the nominal value of 230 Volts, but can vary, In particular, It can be lower than this nominal voltage and, in such a case, the starting torque that such an asynchronous motor is likely to produce has a tendency to quickly decrease. 20 In particular, it is possible that below a voltage of 180 Volts the motor is often unable to start. Therefore, this variability of the supply voltage of the motor should also be taken into consideration for the dimensioning of the latter. Finally, if one takes into consideration all the strains the motorisation of a building 25 closing system or the like of the type roller shutter represents, a person skilled in the relevant art is likely to conclude that a three-phase motor should be used. Furthermore, as soon as one wants a motor with certain performances or one wants to meet particular constraints, a balanced three-phase motor is typically used. A power 30 converter in the form of a speed-varying device is usually associated with a balanced three-phase motor, so that all these requirements can be met.

4 However, for such an application of a three-phase motor with speed variation to a roller shutter, a person skilled in the relevant art is likely to observe that he/she is facing an unavoidable or nearly unavoidable requirement, namely the maximum cross-section the tubular motor can adopt for its accommodation in the winding-up tube of, for example, 5 a roller shutter. A three-phase motor is typically too large a cross-section to allow such an installation, Of course, it can be contemplated to increase this cross-section of the winding-up tube, but this results into a larger cross-section of, for example, a roller-shutter apron when 10 wound up, thus of the box in which this roller-shutter mechanism is accommodated, in addition to the fact that the implications at the level of such a building for the latter to be able of receiving such oversized boxes, For example, their installation in the thickness of a wall can be made impossible. An installation against the inner side of a building causes this voluminous box to be more protruding into the dwelling. In the 15 event of a renewal, a thicker box reduces accordingly the surface for the passing through of light at the level of a window. This is completely contrary to the current tendency consisting in making the box of a roller shutter as discrete as possible and in facilitating its integration into a building. 20 Another solution consists in placing such a three-phase motor at an end of said winding-up tube, instead of integrating it into the latter. This also results into a lateral extension of the box of, for example, a roller shutter corresponding to the additional size created by this motor, which of course results into specific arrangements to be foreseen at the level of the building. 25 As can be observed, although a three-phase motor is well suited for driving an apron of building closing system or the like of the type roller-shutter, it typically cannot be used in this field of application, because of unavoidable dimensional constraints. 30 Therefore, persons skilled in the relevant art have to date systematically turned towards the only motor they believe capable of technically and economically solving the problems of the motorised driving of building closing systems, apparatus, assemblies or 5 devices of the type roller shutter, namely using a single-phase asynchronous motor with a capacitor. It is therefore desirable to at least partially improve, and in a preferred form, optimise 5 operation of a building closing system or the like of the type roller shutter. SUMMARY OF THE INVENTION An apparatus for closing a building, of the type roller shutter, comprising: a. a two-phase asynchronous motor comprising two winding, said motor being associated with a speed-varying device; and 10 b. a roller shutter arranged for actuation by said motor, said motor being associated with an electromagnetic brake; wherein c. said speed-varying device is arranged to subject said motor, at least during an initial starting phase of said motor, to a threshold voltage Vs and a supply frequency fs arranged for release of said electromagnetic brake; and 15 d. beyond said initial phase, said speed-varying device is arranged to vary either voltage or frequency or both voltage and frequency until a substantially constant ratio between an efficient voltage and a frequency is reached. The apparatus may alternatively be a device and in other alternative forms may be a 20 motorised system or assembly. The motor preferably comprises a speed-varying device in the form of a power converter resulting, for predetermined characteristics, in substantially increasing the starting torque these motors should normally produce under the influence of a phase 25 shift created between the main winding and the secondary winding through a simple capacitor. According to the prejudices and customs of a person skilled in the relevant art, and because a three-phase motor typically cannot be used due to typical dimensional 30 constraints, such a skilled person typically has no other choice than to use a single phase asynchronous motor with a capacitor for driving a roller shutter or a similar component for closing a building. The two-phase asynchronous motor of the present 5a invention enables closing of a building to be controlled by a speed varying device in order to meet all the torque constraints the driving of an apron of a system or the like for closing a building, of the type roller-shutter, represents in all possible situations of opening or closing. 5 To date, no speed varying device has been associated with a two-phase asynchronous motor, since this type of motor has always been considered as being a low-cost one for applications in which the use of a motor over-dimensioned with respect to its function had nearly no consequence for the total cost of the thus motorised object or installation.

6 As a matter of fact, when taking into consideration the consequences of an over motorisation in the field of the present application this use of a two-phase asynchronous motor combined with a speed-varying system is counter to a number of prejudices that have been reversed by the present invention. The reversal of these prejudices results in 5 non insignificant advantages which will become clear in the following description, According to a preferred embodiment, the speed variation is based on the principle of a scalar control aimed at causing the frequency of the current supply to vary while maintaining substantially constant the ratio between the efficient voltage and the 10 frequency, in order to achieve a constant flow in the machine and, hence, to maintain constant torque regardless of variation in supply frequency. In particular for a motor with an integrated electromagnetic brake, it has also been devised to control the operation of the motor according to this constant or substantially 15 constant function of the voltage against the frequency, except at the limits, in particular in an initial starting phase where the voltage is chosen different from zero. In fact, this voltage is equal to a threshold value defined sufficient to ensure the release of this electromagnetic brake, which these motors can be provided with in their application to these systems for closing a building, of the type roller shutter. 20 Further objectives and advantages of the present invention will become clear when reading the following description, which refers to embodiments given by way of an indication and as non-restrictive ones. 25 Any references in this specification to "IOBT" and "MOS" are well know by persons skilled in the relevant art and respectively define an insulated gate bipolar transistor and a metal oxide semiconductor. Any description of documents, acts, materials, devices, articles, methods or the like 30 which is included in the present specification is solely for the purpose of providing context for the present invention, It is not to be taken as an admission that part or all of what is described forms part of the prior art base, or was common general knowledge in 7 the field relevant to the present invention, as it existed in Australia or elsewhere before the priority date of each claim of the present specification. BRIEF DESCRIPTION OF THE FIGURES 5 A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying figures in which: - figure 1 is the synoptic view of an asynchronous motor with two identical windings and supplied with current through a speed-varying device according to a first 10 embodiment; - figure 2 is a similar representation corresponding to a second embodiment; - figure 3 is a representation similar to figure 2, showing a third embodiment; 15 - figure 4 is an illustration similar to figures 1 and 2 corresponding to a third embodiment of the invention; - figure 5 represents in the form of a graph the control of the speed variation of the 20 motor through a constant ratio between the efficient voltage and the frequency, over at least one range of this variation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention relates in a preferred form to the application of a two-phase 25 asynchronous motor for driving devices for closing a building, of the type roller shutter. It also relates in a preferred form to a closing device, namely a roller shutter provided with such an asynchronous motor. In particular, according to a preferred form of the present invention, the asynchronous 30 motor 1, as schematically shown in the figures, is of the two-phase type and includes two preferably, but not necessarily, identical windings 2, 3. These windings 2, 3 are connected, through a speed-varying device 5, to the current-supply network 4, for 8 example of a dwelling, which supply is of a conventional type with alternating current, for example with a nominal voltage of 230 Volts and a frequency of 50 Hertz. Advantageously, this speed-varying device is with a scalar control, i.e. designed 5 capable of ensuring a constant voltage-frequency ratio Va/f over at least one determined range of this variation. According to one embodiment, this device 5 is in the form of a power converter comprised of a rectifier 6 and an inverter 7. 10 As regards the rectifier 6, in a first simplified embodiment shown in figure 1, it is defined by a bridge 8 with two diodes Sa, 8b, with which is associated a capacitive divider 9 comprised of a first 9a and a second capacitor 9b connected in series to the terminals of the bridge 8. While the inverter 7 is formed of a switching cell 10, also 15 connected to the terminals of the diode bridge 8 and including two power switches connected In series, of the IQBT or MOS type, 10a, 10b, ensuring the slicing, at the desired frequency, of the rectified current at the outlet of the rectifier 6, in order to ensure the current-supply to the motor 1. To the middle point of this cell, between both switches, are connected the two windings 2 and 3, this through a phase shift capacitor 20 11. In order to allow omitting this phase shift capacitor 11, the control of the inverter 7 imposes the quadrature of the supply currents to the motor 1. This design leads to using two switching cells 10, 10' connected to the terminals of the diode bridge 8 and each 25 comprised of 2 power switches I0a, lOb, 10'a, lO'b, as can be seen in figure 2. Each one of the windings 2 and 3 is connected to the middle point of a switching cell 10, 10', respectively. Advantageously, the inverter 7, thus the switches, is controlled in pulse-width 30 modulation, referred to as MLI control, which, under the inductive effect of the motor 1, results into smoothing the stator currents and into making sinusoidal the currents flowing through the two windings 2, 3 of the motor 1, It should be noted that the 90' 9 phase shift of the current-supply to these windings 2, 3 is ensured at the level of the control. Hence, this Is clearly a two-phase motor. The use of a rectifier 6 defined by a simple bridge 8 with two diodes 8a, 8b, which a 5 capacitive divider 9 is associated with, leads to feeding the terminals of the power switches with a direct voltage Ve - 2x230x 5 , i.e. 650 Volts, starting from an alternating network current-supply of 230 Volts. In order to cope with this problem and as shown in figure 3, the rectifier 6 should use a 10 conventional bridge 8 with for diodes 8a, 8b, 8c, 8d and one single associated filtering capacitor 12. The supply voltage is then reduced by half, Ve = 230,5 = 325V. The voltage constraint on each transistor is therefore reduced by half. In such a mounting, the switching operations of the transistor of the IGBT power 15 switches 10a, lOb ; 10'a, 10'b can create important voltage variations likely to disturb the electromagnetic environment, since the windings 2, 3 are directly connected to the network 4 and permit disturbances to arrive directly at the level of the latter, In order to cope with this drawback and as shown in figure 4, a three-phase inverter 7 20 can be used, which differs from the embodiment of figure 3 through the connection of the windings 2 and 3 of the motor 1, which, instead of being connected directly to the rectified source 4, are connected to a third switching cell 10" of the inverter 7. This third cell 10" in parallel with two further cells includes, like in the case of the latter, two IGBT or MOS power switches 10"a, I 0"b, between which the windings 2, 3 are 25 connected. According to a particular feature of a preferred embodiment of the invention, though the speed-varying device 5 is with a scalar control in order to maintain, during this variation, a substantially constant ratio between efficient voltage and frequency, this is 30 the case only within a range beyond a threshold voltage Vs and, preferably, until a predefined maximum voltage VM, as the graphic of figure 5 wants to show schematically.

10 This feature is in particular interesting when, in an alternative preferred form of the present invention the motor is provided with an integrated electromagnetic brake, rather than an associated electromagnetic brake, operating in the absence of current and the release of which has to be ensured in the initial starting phase. In particular, during this 5 initial starting phase, a threshold voltage Vs is applied to the motor for a determined supply frequency fs, in order to ensure, right from the initial phase of current-supply to the motor 1, the release of the electromagnetic brake. Then, the frequency (as the case may be, the voltage, or both frequency and voltage) is caused to increase until the V/f ratio reaches the value of the constant one wants to maintain during the speed variation. 10 Beyond the latter, the voltage and the frequency preferably increase simultaneously. This first starting step is shown by means of the flat line 13 on the curve of the graph of figure 5. Advantageously, this constant value of the Van/f ratio is equal to the value of the 15 efficient voltage on the network 4 at the nominal frequency of this network, i.e. for example 230 Volts/50 Hertz. As also shown by this graph, trials could show that a supply voltage of at least 10 Volts, preferably in the range of 50 to 70 Volts, allowed achieving the release of the 20 electromagnetic brake, As a matter of fact, one advantage deriving from the present invention consists in that this brake-calling force is much higher, due to a lower frequency during starting, compared to a motor fed directly through the network, 25 Therefore, this electromagnetic brake, which is a part subject to substantial wear in the current motors, can preferably be very easily be optimized in this case. In particular, it can be enhanced as to its design, so as to preferably achieve not only a 30 longer lifetime, but mainly in order to react with less inertia and to achieve a better looking of the driving mechanism of a roller shutter, of course for a higher safety.

l1 Advantageously, the maximum supply voltage VM of the motor 1 beyond which the

V

0 df ratio is no longer maintained constant corresponds to the efficient value of the voltage of the current-supply network 4, for example 230 Volts. It should however be noted that any value can be chosen for this voltage VM, and that the present invention is 5 in no way limited to it. In comparison, as regards the frequency variation, in a preferred form of the present invention, since it depends on the control for switching the power switching, it can largely exceed the frequency of the network. 10 It should be noted in this respect that, since, at a network supply of the type 230 Volts 50 Hertz, the asynchronous motors with main and secondary windings and provided with only one pair of poles were necessarily subjected to a speed of rotation of 3,000 rev/mn, the speed-varying device 5 according to a preferred from of the present 15 invention, leading to a higher torque through a lower speed of rotation, permits to contemplate subjecting these motors to a lower maximum speed of rotation, for example in the range of 1,500 rev/mm. This results into a substantial reduction of the magnetic and mechanical vibrations with, 20 here too, an inertia gain at the level of the reactivity of the electromagnetic brake and less slipping. To this should be added that the advantages of a preferred form of the present invention allow a lower reduction ratio, thus a higher mechanical efficiency. Finally, it should also be observed that a preferred from of the speed-varying device 25 according to the present invention permits, during the various phases of the control of a closing system of the type roller shutter for its opening and closing, to carry out decelerations and accelerations, thus avoiding the noises due to a sudden change, in particular due to a sudden stoppage. 30 This advantage obviously results in applying less load to mechanical components, the lifetime of which is therefore improved.

12 Though it meets the constraints related to the driving of systems or the like for closing buildings of the type roller shutter, this two-phase asynchronous motor can, in a preferred form have a tubular shape, so as to be capable of being accommodated in a winding-up tube for the apron of such a roller shutter. This motor, with performances 5 comparable to those of a three-phase motor, does indeed not have the size of the latter and keeps the dimensions corresponding to a single-phase asynchronous motor with a phase-shift capacitor. As clearly appears from the preceding description, the present invention provides 10 substantial progresses in the field of the motorisation of systems, apparatus, assemblies, devices or the like for closing a building of the type roller shutter. It will be appreciated by persons skilled in the art that numerous variations or modifications may be made to the invention as described in the specific embodiments 15 without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (32)

1. An apparatus for closing a building, of the type roller shutter, comprising: a, a two-phase asynchronous motor comprising two windings, said motor being 5 associated with a speed-varying device; and b. a roller shutter arranged for actuation by said motor, said motor being associated with an electromagnetic brake; wherein c. said speed-varying device is arranged to subject said motor, at least during an initial starting phase of said motor, to a threshold voltage Vs and a supply 10 frequency fs arranged for release of said electromagnetic brake; and d. beyond said initial phase, said speed-varying device is arranged to vary either voltage or frequency or both voltage and frequency until a substantially constant ratio between an efficient voltage and a frequency is reached. 15

2. An apparatus for closing a building as claimed in claim 1 wherein said substantially constant ratio is maintained.

3. An apparatus for closing a building as claimed in claim 2 wherein said speed-varying device comprises a scalar control, said scalar control being arranged to ensure said 20 substantially constant ratio V/f is maintained over at least one predetermined range of said variation.

4. An apparatus for closing a building as claimed in any one or more of the preceding claims wherein said speed-varying device comprises a power converter, 25

5. An apparatus for closing a building as claimed in any one or more of the preceding claims wherein beyond said initial starting phase said speed-varying device causes the frequency to vary until said constant ratio is reached. 30

6. An apparatus for closing a building as claimed in claim 5 wherein during said starting phase after said constant ratio is reached, said constant ratio is maintained until a constant supply voltage of a power supply supplying power to said motor is reached. 14

7. An apparatus for closing a building as claimed in any one or more of the preceding claims wherein said substantially constant ratio comprises a predetermined maximum voltage VM. 5

8. An apparatus for closing a building as claimed any one or more of the preceding claims wherein said frequency comprises a frequency of a current-supply network to which said motor is connected. 10

9. An apparatus for closing a building as claimed in any one or more of the preceding claims wherein said voltage comprises a voltage of a current-supply network to which said motor is connected.

10. An apparatus for closing a building as claimed any one or more of the preceding 15 claims wherein said substantially constant ratio is equal to the tension efficient voltage at a frequency of a current-supply network to which said motor is connected.

11. An apparatus for closing a building as claimed in claim 10 wherein said power converter comprises a rectifier and an inverter. 20

12. An apparatus for closing a building as claimed in claim 11 wherein said rectifier comprises diodes.

13. An apparatus for closing a building as claimed in claim 12 wherein said rectifier 25 comprises a bridge having four diodes.

14. An apparatus for closing a building as claimed in claim 11 wherein said inverter comprises a power switch. 30 15. An apparatus for closing a building as claimed in claim 14 wherein said power switch comprises one or more of the following switches: IGBT or MOS.

15

16. An apparatus for closing a building as claimed in claim 14 or claim 15 wherein said inverter comprises two switching cells connected to terminals of said bridge and two said power switches in series, each one of said primary and secondary windings being respectively connected to the middle point of a corresponding switching cell. 5

17. An apparatus for closing a building as claimed in claim 16 further comprising a third switching cell comprised of two power switches in series between which said primary and secondary windings are connected. 10

18. An apparatus for closing a building as claimed in any one or more of the preceding claims wherein said windings are identical.

19. An apparatus for closing a building as claimed in any one or more of claims I to 17 wherein said windings are not identical. 15

20. An apparatus for closing a building as claimed in any one or more of the preceding claims wherein said roller shutter is arrange to close said building.

21. An apparatus for closing a building as claimed in one or more of claim 19 and 20 claim 20 wherein said two-phase asynchronous motor is tubular and arranged for housing within a winding-up tube of an apron of said roller-shutter.

22. An apparatus for closing a building as claimed in any one or more of the preceding claims wherein said threshold voltage is fixed. 25

23. An apparatus for closing a building as claimed in claim 22 wherein said threshold voltage is greater than zero,

24. An apparatus for closing a building as claimed in any one or more of claims 1 to 21 30 wherein said supply frequency is fixed. 16

25. An apparatus for closing a building as claimed in claim 24 wherein said supply frequency is greater than zero.

26. An apparatus for closing a building as claimed in any one or more of the preceding 5 claims wherein said apparatus comprises a device.

27. An apparatus for closing a building as claimed in any one or more of claims 1 to 25 wherein said apparatus comprises a motorised system. 10

28. An apparatus for closing a building as claimed in any one or more of claims 1 to 25 wherein said apparatus comprises an assembly.

29. An apparatus for closing a building substantially as herein described with reference to any one or more of the accompanying figures. 15

30. A device for closing a building substantially as herein described with reference to any one or more of the accompanying figures.

31. A motorised system for closing a building substantially as herein described with 20 reference to any one or more of the accompanying figures.

32. An assembly for closing a building substantially as herein described with reference to any one or more of the accompanying figures.